text:
What is meant by a "pressure system" in FAR 91.205?
FAR 91.205 states:

§ 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.

(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:
  ...

(5) Oil pressure gauge for each engine using pressure system.

What is a "pressure system" in this regard?
Background: Our aircraft has an oil pressure gauge that erroneously reads high pressure. The A&P checks this every year and notes that the oil pressure is within the normal range.
EDIT: "I guess I should be clear about what "erroneously high" means, the gauge pegs the needle so it isn't just a little high". – Ron Beyer
The sender has been replaced and the only thing left is the gauge. We've been flying like this for years. Recently one of our CFI's has determined that we are in violation of 91.205 and has told us to ground the aircraft until it can be repaired.
Have we been flying against FAR's? Is a "pressure system" meant to mean a pressurized oil system, or does it mean an aircraft with an altitude engine? Like I said, our A&P (two different ones in fact) have signed off on this since the engine was replaced 10-ish years ago.

EDIT:    With the additional information that the oil pressure gauge is "pegged", the CFI is correct in calling it un-serviceable.
It sounds like the A&P has checked the engine oil pressure with another means and finds that the actual engine oil pressure reading is within limits. The A&P then signs it off thinking that a correct gauge reading is not required. The A&P is incorrect as a serviceable gauge is required as per FAR 91.205
Oil pressure gauges are required for engines with pressurized lubrication systems,  but not for engines with "splash" oiling.
Older engine designs, and may of today's smaller engines (like lawn mowers), use a "splash" oiling system that does not supply oil under pressure to the bearing journals, or to other friction points in the engine.
In a "splash" system, oil is applied to the cylinders and pistons by rotating dippers on the connecting-rod bearing caps. As they they rotate, the dippers pass through the oil pan and slash oil into the areas that require lubrication.

If the oil pressure gauge in your "pressure system" is reading high, outside acceptable limits, it should be replaced. It is easy to confirm using another gauge. High oil pressure can also be caused using the wrong viscosity oil, incorrect pressure relief valve on the oil pump, or bearing clearances that are to tight.
High (or low) oil pressure could cause an engine to fail. If the gauge was out of calibration, it would be impossible to tell what the actual pressure was. If you are accustomed to seeing high oil pressure, how could you possibly identify what was too high, or what was too low?
I would not want to fly any aircraft with an inaccurate oil pressure gauge because it would rob you of valuable time to deal with an engine that might fail at any time.

"The A&P is correct that the high oil pressure readings should be addressed" The A&P keeps signing the aircraft off at annuals even when explicitly being asked about this issue, it's the CFI who is telling us to get it fixed...

I guess I should be clear about what "erroneously high" means, the gauge pegs the needle so it isn't just a little high.

@RonBeyer that means the gauge is clearly unserviceable, as in completely useless, and you really shouldn't be flying it.  I could see a condition where you are told to subtract 5 PSI from the guage indication for actual, although I would say this would require a calibration placard on the panel to be valid (the information has to be available to anybody flying).  At minimum the CFI would be correct to refuse the fly the plane as PIC.  Whether it's grounded or not it's up to you.  My mind is boggled that an A&P would sign off on an unserviceable critical item like that.

It just means an engine using a pressurized oil system to the main and cam bearings. These systems require oil pressure to keep the metal of the bearing and the journal separated, as opposed to roller or ball bearings where there is direct rolling metal contact and the oil only needs to be splashed (radials use roller/ball bearings typically for the main journals).  A pressurized oil system normally never has metal to metal contact at the moving interfaces except when starting, and if you ran such an engine without ever stopping it but just replaced the oil, the bearings would theoretically last forever.  So the pressure is actually a critical item especially at takeoff power.
I think technically the CFI is right, in that the guage is unairworthy insofar as it reads incorrectly and the green arc is a go-no-go item.  If the A&P added a placard with a correction factor, maybe that gets into a grey area legally speaking and could be allowed, but really it should be fixed and I'm surprised the mechanic would sign that off just saying "it's fine".


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Did Japan actually use any production aircraft with inverted gull wings during WW2?
The anime film The Wind Rises presents a fictionalized account of Jiro Horikoshi and the development of the Mitsubishi A5M. Throughout most of the anime, Jiro visualizes the plane with this shape:

I recognized this shape from a production aircraft, but being rusty on my WW2 aviation knowledge, assumed it was the A6M Zero (the designation is never stated in the film). In reality, the production A5M and A6M had fairly straight wings, but the prototype A5M (which is what is depicted in the film) had inverted gull wings:

I then realized that the inverted-gull wings aircraft that I was thinking of was an American fighter, the somewhat similarly-shaped Vought F4U Corsair:

This got me curious on whether any production aircraft used by the IJN (or any branch of the Japanese military) during WW2 used inverted gull wings. From the photos and diagrams I can find, it looks like Japan stuck exclusively with straight wings, but some aircraft are depicted from a side view where it's very difficult to discern the exact shape of the wings.
Did Japan actually fly any production aircraft with inverted gull wings during WW2?

Nice research effort (I've up-voted). It would be better to also include the citation of "the prototype A5M (which is what is depicted in the film) had bent gull wings":
https://en.m.wikipedia.org/wiki/Mitsubishi_A5M

@RayLuo Thanks! I updated with a link to the Wikipedia article.

At least one - the Aichi B7A - although it saw little action, coming very late to the war.

The Aichi B7A Ryusei (愛知 流星艦上攻撃機 Aichi ryuusei-kanjou-kougeki-ki)
("Shooting Star", Allied reporting name "Grace") was a large and
powerful carrier-borne torpedo-dive bomber produced by Aichi Kokuki KK
for the Imperial Japanese Navy Air Service during the Second World
War. Built in only small numbers and deprived of the aircraft carriers
it was intended to operate from, the type had little chance to
distinguish itself in combat before the war ended in August 1945. (source)

 (source)
 (source)
The director of The Wind Rises Hayao Miyazaki may also be familiar with another Japanese gull-wing design, the Kawanishi E11K "Laura" flying-boat, which too saw service in WW2. However, its wing is not inverted.
 (source)

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Why is this plane circling around the Lucknow airport every day?
Saw this plane circling around Lucknow airport (LKO).
This is happening every day. Any idea what is happening?

NATS UK 24: https://youtu.be/a8CQ29yWvZI?t=97

That is a plane being used to train/practice landings.
It is without passengers and one of the pilots is training. There will also be another pilot on board, possibly two, providing support and checking that the trainee is performing their duties according to the manual.

Or maybe a test flight?

@DeepSpace being an airline, not a manufacturer, I see that as unlikely

I would guess that if someone were to look up the approach plates for LKO, they'd find that the flight path follows a standard approach, too.

@Federico I'm pretty sure that airlines do test flights a lot of times. After C-Checks/D-checks for examples.

@DeepSpace personally, I never heard of such a test flight having the pattern shown in the question.

If it is indeed a new pilot, when coming in for a landing, he'll hopefully be in luck now.

@Baldrickk Haha, wow, it took too long for me to see that. :)

@Baldrickk Landing isn't the problem.  It's leaving when you're out of... (oh, dear...)

@Federico, What does the track of a post-maintenance checkflight look like?

@MichaelHall: https://www.flightradar24.com/blog/making-sure-an-aircraft-is-ready-to-fly/?utm_campaign=website&utm_source=sendgrid.com&utm_medium=email and for normal testing: https://www.flightradar24.com/blog/interesting-patterns-on-flightradar24/?utm_campaign=website&utm_source=sendgrid.com&utm_medium=email

@GiacomoCatenazzi, Thanks, but I was being a little bit facetious with Federico...  Your links make the point that you can't really say that the track in the original question does, or does not, resemble a PMCF.

@MichaelHall I think that the second link makes exactly that point. "Other pattern work" is exactly what we have in the question vs "flight test" (post maintenance or not)

I don't understand your point.  And the second link looks more like a search grid than anything else.

@MichaelHall scroll down the page

Ah yes, I didn't scroll.  So, I think we agree... right?

@DeepSpace according to Wikipedia, aeronautics is a major industry in Lucknow.  So maybe it is some sort of test flight.

I asked Lucknow Airport via their official twitter. Their response was, erm, terse.

Q: Why does Indigo flight 6E8002 circle Lucknow Airport every single day for an hour?
@aailkoapt (LUCKNOW AIRPORT): Training Flight.
Per Twitter - Mar 16

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Is it possible for an airplane to produce thrust from compress air without using fuel?
Is it possible for an airplane to fly as it compress the atmospheric air during flight?

Sure, but how does the air come to be compressed? Compressing air requires energy of some sort and "fuel" happens to be a particularly efficient form of energy storage, especially when you're interested in getting the most energy per pound.
There was an early (1879) model airplane with a compressed air engine and small compressed air model rockets are certainly possible. There are a lot of practical concerns with filling a large airliner on the ground with enough compressed air for a flight.

Yes.  The problem is that you cannot compress a gas to store anywhere near as much energy as petrol or diesel.

related: http://aviation.stackexchange.com/q/17648/1467 http://aviation.stackexchange.com/q/14710/1467

we use electric motor installed in the jet engine. we use the same jet engine layout but without fuel and combustion chamber.

So basically you're describing an electrically powered aircraft (like the prototype Airbus E-Fan, which uses two electrically powered ducted fans and a motor-driven wheel on the gear to help with takeoffs). There's no reason for it to be a jet at that point, it's just a motor turning a fan. This leads to the next question: where does the electricity come from? It has to be generated and stored somewhere. And jet fuel stores far more energy per pound than any available battery technology.

yup, that's the problem

If the energy source weight is the problem then this question is relevant: Battery Vs Combustion Energy/Weight Efficiency and it boils down to the specific energy or energy density.

First of all, where does the compressed air come from? Is it stored in big tanks, or do you compress it as you fly?
Assuming you use the second way (the first would be quite inefficient), you need to power the Air Compressor, which means you need to generate energy.
If you do not want to use fuel, then it has to be powered by electricity, i.e. an electric plane. This is basically how the Airbus E-Fan works, using two ducted fans powered by electricity (as @Zach Lipton said in the comments)
So to answer your question, yes, your theory works. There are already a few prototypes using it.

yes, the second option, thanks

Yes, but by the time you're to the point of the E-Fan or a similar aircraft, you're not really talking about an aircraft powered by compressed air anymore. You've just got a fan, and that's no different from every prop out there.

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Is the word “bomb” muted in inflight movies?
I was recently on a transatlantic flight and watched the movie Steve Jobs on the plane’s entertainment system. Every movie I tried, including that one, had a message right at the start saying the movie had been edited for content.
In one scene, the caracter of Steve Wozniak is fiddling with a watch and the character of Steve Jobs makes a joke it looks like he’s messing with a bomb. Those words were muted. The word “bomb” (and one or two words around it) were gone from the movie. I even rewinded to make sure, and the words were indeed gone.
Is there some weird law that forbids the use of the word in inflight entertainment systems? It there is, it’d be particularly weird since you need to plug headphones to listen to the movie in the first place, so it’s unlikely you’d cause hysteria. In addition, the word was pronounced again later on in the movie but wasn’t muted then. It was less clear audibly, though, so it’s feasible it wouldn’t have been caught by the automated system (if any is used).
The airline was TAP, and the entertainment systems are individual per seat.

I'm voting to close this question as off-topic because it is about passenger aspects and should be posted on http://travel.stackexchange.com/

While the flight entertainment system indeed is about passenger aspects, censoring several words may be done due to safety reasons. In this case, the questions belongs to av.se. (However, I imagine the word "bomb" not being muted. Passenger: "Oh, they said 'bomb'. A bomb can take aircraft down! I'll going to panic in 3...2...1...". And the terrorist: "Ah, yes, sorry, I forgot about. See you in heaven in 3...2...1...") (Oh, and did I trigger a red light at any agency now?)

@RonBeyer inflight-entertainment already existed as a tag, which further reinforced to me I was asking in the right pace. No quarrels with transferring the question if it’s an issue, though.

@user137369 The wording on that tag description isn't the best, but I believe that it is about the entertainment systems themselves, not the content they display. The content is chosen by the airline in accordance with local, regional, or cultural considerations and is not mandated by the aviation regulatory bodies.

@RonBeyer I see. Is it possible to directly transfer the question to the correct Stack Exchange site?

You can flag it for moderator attention, or just start a new question on the appropriate site, which is probably the easier route to go.

@RonBeyer Asked and answered on the appropriate site. Feel free to close/delete.

This might be dependent on the airline?
I usually fly Emirates and the movies are not muted for the word "bomb". Maybe because each seat has its own entertainment console?
In the old days when there was one giant projector that displayed movies (which was later replaced by TVs that articulated from the ceiling) - I suppose in these scenarios it might be prudent to mute words or scenes.

To be clear, the entertainment console was individual in this case, as well.

Even in the Good Ol' Days™ of a single (or several) public screens, you had to plug your 'stethoscope' headphones into the jack in order to listen to the movie, so even then, the word bomb wouldn't have been broadcast throughout the cabin.

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Why do airplanes have rounded windows?
Why are the windows of an airplane usually rounded at the edges?

<style>border-radius:50px;</style> That's about it for a programmer :P

That's HTML, probably not used for airplanes :)

@Iceman that CSS is lexically incorrect.. :P

Airliner (Browser) Compatibility you know :)

Seems it's valid CSS: window{color:white;border-radius:15cm}

Perhaps the same reason why port holes are round in ships too?

the windows are round because the holes they make in the fuselage are round.

And the holes in the fuselage are round because fitting a square peg in a round hole involves some retrofitting (top image; also here) that would look rather ugly on a commercial aircraft. Q.E.D.

@GustavoRodrigues that code is invalid for U.S. Registered Aircraft. Welcome to the Imperial System. We've jot jackets.

A pressurized fuselage needs rounded corners at all cut-outs to avoid the accumulation of stress in corners. If the corners were not rounded, the fuselage skin would need to be locally reinforced, or it would begin to crack there soon.
This was learned the hard way by de Havilland, when their Comet jet airliner began to plunge out of the sky for unknown reasons. In one of the first major crash investigations in aviation history, the wreck of one was lifted from the seafloor off Elba and re-assembled. Then it was learned that the pressurized cabin had burst from cracks emanating from the window corners.

de Havilland Comet I. Note the square windows. The window which caused the destruction of G-ALYP was on top of the fuselage and cannot be seen in this picture. (Picture source)

Finite element simulation of corner stresses in a Comet fuselage skin.  Red denotes the highest stresses. (Picture source)
Other aircraft companies had built pressurized cockpits twenty years earlier and did it right the first time …

A note on the Havilland: The cracks where detected not by reassembling the body but by building a full size container and using water to pressurize and depressurize: https://en.wikipedia.org/wiki/De_Havilland_Comet - gvf

If the corners were not rounded, the fuselage skin would need to be locally reinforced .. How much re-inforcing would the 90 degree angled corners require? And would re-inforcing really solve the problem? Did anyone try it again?

@Firee: In theory, a sharp corner needs an infinite reinforcement. In reality, the reinforcement is stretched out but will still need to be substantial, and would need to have rounded corners itself, so the cutout becomes bigger. Stiffness in the straight part of the window frame would then be much lower, so it would attract less stress. Rounding the corners is simply the better approach.

Oh well, so much for triangular or hexagon or pentagon windows, in the name of design

@securitydude5: Actually, at least one pressurised jetliner (the Caravelle) did have triangular windows (see here, for instance) - they just had to be rounded triangles.

@Sean. Right. Oval windows were also used with success, see here

Stress Distribution / Stress Concentration
The sharper you make a corner, the higher the stress will be. This is undesirable since it will increase the stress on the material and can promote fatigue which can lead to structural failure down the road.
You can avoid this problem by having a greater curve radius. This does not only apply to windows, but cabin/cargo doors as well on an aircraft.

Source
When aircraft undergo conversions become freighters and add cargo doors, you will notice that they need to make the metal thicker around the door to help distribute stress, hence the area of unpainted metal:

(source: transportarchive.org.uk)
Source
Calculation
Some material on this, although it make the simplification the stress is only in one direction rather than both as in real life. You can see how as $r$ becomes smaller the stress concentration $K_t$ goes up, raising the maximum stress ($\sigma_{max}$).

Footnote: There will have to be a little bit of 'play' between the window and fuselage for technical reasons, such as thermal and pressure expansion, making this type of arrangement necessary. If you could perfectly carry over the load in every direction to the window this would not be necessary.


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Has the typical cabin pressure in airliners changed in recent decades?
Two or three decades ago, I would experience quite uncomfortable blocking of the eustachian tubes, which would noisily unblock and become blocked once more as the plane descended.
I haven't experienced that in recent years, in which I have been flying on considerably newer aircraft.
Is this likely to be a change in the cabin environment or my own physiology - that is, have cabin pressures generally increased so that changes during descent are less dramatic, or have I just become older and less susceptible to blocked ears?
Recent airliners such as the 787 and the A350 have much-touted higher cabin pressure levels; has there also been a general increase in standard cabin pressures over the years?

No doubt older airlines had a lower max differential pressure as @ymb1 pointed out.  More likely though is the fact that modern aircraft have automatic pressurization systems that are designed for maximum passenger comfort as the cabini altitude climbs and descends.
Older manual pressurization systems required a pilot to monitor and adjust the pressurization system anytime the aircraft changed altitude or power settings.


text:
What measures can the aerospace industry take to deal with changes in the electronic industry that are incompatible with its own conservatism?
The development of computer flight systems is characterised by lengthy certification processes, exceptionally rigorous testing regimes and a default position of extreme caution.
A change in any component at any layer in the hardware/software stack could introduce new incorrect behaviour. For example, microprocessors are so complex that different manufacturing revisions of the same model can introduce bugs.
As a result, these systems are very tightly specified at all levels and very slow to change, so that many systems still in production use what in most other contexts would be considered obsolete technology.
CPUs such as the 68040 and 80486 (both introduced around 1990) were designed into systems a quarter of a century ago that are still being produced today.
Summary of the problem
The pace of development of the electronics industry has accelerated hugely since the first generation of computerised flight control systems were introduced in the early 1970s, and is becoming increasingly incompatible with the needs of the aviation industry. It means that for example:

Devices now have manufacturing lifetimes of just a few years (compared with several times that a few decades ago).
Devices are now intended to have much shorter service lives than they used to (by orders of magnitude).
Increasingly tiny widths in microprocessors mean they succumb increasingly early to problems such as oxide breakdown.

Aerospace represents a very small portion of the manufacturers' business: their main customers make consumer devices, and have utterly different demands on the electronics industry from those of customers in aviation.
Research into the issue
These and other issues are outlined in some detail in Microelectronics Reliability: Physics-of-Failure Based Modeling and Lifetime Evaluation (and no doubt elsewhere - this was just one I found while trying to answer my own question).
The Aerospace Vehicle Systems Institute (AVSI) Consortium Project #17 Methods to Account for Accelerated Semiconductor Device Wear Out has attempted to quantify these risks.
The question
What can the aerospace industry do - or what is it already doing - to mitigate the problems and risks this poses?

Can you cite the use of 68040 and 80484?  Are you talking about simply "hobbyist" avionics such as handheld GPS or commercial aviation?  What are the problem and risks that you see?  Why does avionics need to move more quickly?  If it does the job and does it well, why change?  The drivers for aviation are very different than for consumer goods.  I think you would need to cite concrete problems and risks in order to start to get answers.

You don't really point out any problems here, just that the technology is older. Are you talking about availability of parts or what. Seems like it's not really a problem that aviation specific items have to be made to higher tolerances. That's why they cost more.

Aerospace isn't the only user of these parts: automotive, medical, petrochem, and other industries also need hardened, certified microprocessors. Like Tom, I'm not seeing any "problems and risks" here. Consumer electronics is just a different industry.

The problem is not that aerospace uses older technology, nor that it should change this. The problem is that trends in the electronics industry are becoming increasingly at odds with those of the aerospace industry. Aviation relies on service and manufacturing lives of devices that run into decades; the electronics industry wants to produce devices with lives measured in months.

@Simon for example, the latest GE 2907C1 FMC in the 737 uses a Motorola 68040.

The chip foundries and the device manufacturers are not the same industries. I believe foundries are happy to produce "simple" chips with modern tooling as the rate of defects is minimal and the profit higher. But there are also more recent circuits developed for avionics. This GPU SoC is based on ARM Cortex A9, which is also used on many smartphones. The i.MX 6 itself is a 40nm-VLSI announced in 2011.

@Federico in the paper I cite in the answer below -  https://nepp.nasa.gov/files/16365/08_102_4_%20JPL_White.pdf - "[Avionics and other systems with similar critical safety requirements] are built with the assumption that electronic components will last for decades without failure. However, counter to this assumption, [...] manufacturing foundries are designing microcircuits for a three- to seven-year useful life, as that is what most of [i.e. not aerospace] the industry seeks." The preface discusses how this affects industries like aerospace.

The question cites a research paper that raises the question, backed by an aerospace industry consortium. It has been a well-known issue in the industry for decades. The risks are clear and well-understood, if not widely-understood. What exactly is not clear about the question, or lacking in concreteness?

The answer is how they will continue to get outdated technology sourced, is the same as everything in aviation, they will charge out the nose for it. There is a reason an avionics box that simpler than a 100 USD tablet costs 50,000 USD. The same could be said for any component on an aircraft, the volume is extremely low compared to most industries.

Do you mean 80486, not 80484?

@Sean Of course, thanks. Weird no-one noticed it.

The aviation industry is strongly cognisant of these risks.
At least one research programme has attempted to analyse them in depth, the Aerospace Vehicle Systems Institute (AVSI) Consortium Project #17 Methods to Account for Accelerated Semiconductor Device Wear Out.
The project ran for six years until 2007 with a budget of ~US$1.2 million.
However, the project's scope was analysis, development of guidelines, testing methods and so on, and did not include ways of addressing the fundamental problem.
A paper from the project Microelectronics Reliability: Physics-of-Failure Based Modeling and Lifetime Evaluation discusses some of the issues in depth.

This is only a partial answer to my own question. If anyone has more information about this project or related initiatives, I'd be interested to know more.

I think you're conflating the PC industry, and its push with Moore's law, with electronics in general.
A huge amount of electronics are used for safety-critical applications. The avionics industry is only a part of it. The automotive industry, in fact, is the leader. Systems like engine computers, electronic power steering, airbag systems, are all long-life safety-critical devices.
Medical devices, industrial systems like robots and elevators, and even appliances like a oven, can cause severe injury and death if they fail. So in many ways, the problem is getting easier, as demand for embedded systems increase.
As an example, you wouldn't use a 80486 or m68k in a safety-critical system. You'd use a chip with an ARM Cortex-R52 core which has specific hardware for lock-step operation, integrated self-test hardware, certification documentation, and more.
Today, there is a big enough market that there are fabrication processes, designs, validation specs, and market availability for long-lived safety-critical devices. Simply search "automotive processor" "SIL CPU" or "automotive grade electronics" and you'll find plenty of systems.


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To what extent (if any) is it possible or desirable for the pilot of a large airliner to "fly by the seat of the pants"?
I recall that some years ago the pilot of the A340'S first flight described its handling as "like riding a bicycle" (to me this would mean that as he went past his favourite bar he saw his friends inside so he propped it up against the wall to have a drink with them).
I can believe that despite its size and weight a large airliner would respond precisely to commands, but does the concept "flying by the seat of the pants" apply to such an aircraft?
Obviously experience and training will build up a great deal of intuition (visual, vestibular, etc) - what sort of bodily connection does an airline pilot experience with the aircraft? Is it markedly different from that of the pilot of a small plane?

Why the question has been downvoted? Explain at least...

@mins After hours and hours in a faithful simulation, would it surprise anyone if the real plane feels the same? Even the true control forces are replaced by springs, the same as in the simulator, so of course the plane feels familiar and easy to fly.

I wait for @Terry to answer this one!

I don't understand why this question was closed as "unclear what you're asking", they are asking if "seat of the pants" flying applies to larger craft and, if it does, how it might differ from "seat of the pants" flying in smaller planes.

I can believe that despite its size and weight a large airliner would respond precisely to commands, but does the concept "flying by the seat of the pants" apply to such an aircraft?

The phrase "flying by the seat of the pants" is an imprecise term, and I don't have an answer for that. However, if you allow it to mean operating an aircraft in the absence of instrumentation or other capability that is normally used, or using techniques not normally used, whether you're forced to because of failure(s) or because you prefer not to use them, then here is an observation.
In the early 1990s I was flying 747-100/200 freighters. The carrier had a contract with Japan Air Lines to haul freight between Tokyo Narita and KJFK, with a crew change and refueling at Anchorage. We used a JAL call sign. JAL had their own 747-200 freighters on the route as well, more of them than our small number of aircraft. Many of their flights would have an American flight engineer who would handle the radio going into U.S. airports. Thus, the Anchorage controllers could not tell from the radio communication whether the flight had American or Japanese pilots.
One summer Anchorage took the ILS down for extended maintenance. One severe clear day during this period we were on our descent but still well out when Anchorage approach cleared us for a VOR approach. We immediately called the airport in sight and requested a visual approach, which was granted.
Curious, when we were down I called approach control on a land line and asked why we were first assigned a VOR approach. They explained that, believing our flight probably had Japanese pilots, and having had those pilots always refuse the offer of a visual approach and request a VOR approach (in spite of the additional 10 minutes of flying), approach control had simply assigned the VOR approach.
As part of our contract, we occasionally had a Japanese check captain observe us, and the next time this happened, I brought up the subject with him. He explained that their pilots were never taught to simply look at a runway and land without reference to navigational instruments, and, lacking a robust general aviation segment, their pilots simply never had experience with doing that. He added that from their standpoint, we were a bunch of cowboys. Not the exact "flying by the seat of the pants" wording, but the same sentiment.

Obviously experience and training will build up a great deal of intuition (visual, vestibular, etc) - what sort of bodily connection does an airline pilot experience with the aircraft? Is it markedly different from that of the pilot of a small plane?

When you're flying the same airplane type day in and day out, you internalize what that aircraft can do and how it will respond. You get used to its noises and even to its vibrations if you will. And regardless of how small or how large it is, it becomes the right size, neither little nor big, especially once you're in the air. When you change airplanes, and especially if it involves a significant change in size, there is a difference.
For example, I spent the last 10 years of my career on 747-100/200 aircraft. Fifteen years after retiring, and not having been in a cockpit during that time, I went out to a local airport to check out in a Cessna 172. I knew I would have trouble with flaring too high, and I warned the instructor. My first landing was a real lesson, actually to both of us. When I said to him, "I think I should flare," he said, "you're way to high." When I said, "I've got to flare,: he said, "still too high." When I said, "I'm flaring," with the sense that if I didn't I would prang the airplane, he said, "you're still a little high, but go ahead." It took me 5 hours to check out in the airplane, most of that time for landings.

Sorry, I didn't mean to stop there @Terry. The first part doesn't quite address the question I was after (you discuss the question of reference to navigational aids - or not), but the second is spot-on. If you'd care to expand with anything further (from personal experience, how pilot training addresses it, any more information on that process of internalisation, etc) that would be very welcome. In particular, can you say anything about the non-visual component of that relationship with the aircraft and to the art of flying - Is it taught or encouraged? Can it be done without? Can it mislead?

Note that "flying  by the seat of one's pants" originally meant flying without fancy instrumentation, as you assumed here,  It only came to have the more general and metaphorical meaning later: http://www.phrases.org.uk/meanings/139400.html

"Flying by the seat of your pants" can be a real problem when your instruments don't agree with your pants. There have been several major accidents where the pilots became convinced that their instruments were wrong, and they were actually right.

That early-90s check captain - sounds like the mindset warned against in that "Children Of The Magenta Line" lecture about the perils of automation dependency. Except the 747-100 and -200 didn't usually have EFIS, did they?

@JackDeeth No EFIS on 747-100/200 aircraft whatsoever that I am aware of.

As long as they are operating in VMC it's certainly possible. The difference in handling from a small aircraft are due to the difference in inertia, wing shape and consequent stall characteristics do certainly not preclude flying "by the seat of the pants".
So: possible yes. Desirable and common: probably not.
Although there are frequent calls for airline pilots to hand fly the aircraft more regularly to counteract the decrease in flying skills that is the inevitable result of increased automation, "seat of the pants" is not just hand flying: it's hand flying by reference to the visual and sensory inputs of the pilot without consideration of the flight instruments (e.g. judging the airspeed using a visual estimation of the angle of attack and how the airplane responds to small changes in input pressures, etc, instead of looking at the airspeed indicator).
I don't think it would be considered safe or even legal operating procedure for an airline pilot to completely ignore the flight instruments. It's certainly not part of any airlines SOP.

I'm not sure this answers the question.

@egid you're right. I refocused the answer.

Ask Captain Al Haynes and Captain Chesley Sullenberger.
Do not ask the Asiana crew who landed short at SFO.
So the answer is:  It depends on the individual crew members and their level and quality of experience.

I'm not sure which accident at SFO you're referring to, but more to the point, what does the race of the pilots have to do with anything?

Quite sure he refers to Asiana 214. If the crew consult instrument and follow procedure properly accident maybe avoided. Thus seat of pants is not a reliable means. Agree that this answer could be expanded. As of now it is too short.

@ZachLipton It is not the race of the pilots that is relevant, but the culture from which the pilots come. In Japanese and Korean cockpits there was a culture in the past that captains would not be challenged. Back in the days of three-man cockpits both KAL and JAL, as I remember, employed American crew members to counter this, knowing that, for example, an American f.e. would have no problem challenging a captain if need be.

Well the pilots in Asiana 214 were Korean, not Chinese as he originally stated, but in any case. I agree that culture makes a difference, and there's been a lot of human factors research on precisely that issue, but I really don't see how it answers the question to say that two [American] pilots did incredibly well in two cherry-picked extremely difficult situations and a crew of [some other country] pilots screwed the pooch in one cherry-picked routine situation. I'm also not quite sure what the question is to be honest: is it flying by the seat of your pants if you still look at instruments?


text:
Which CPUs and programming languages are used in new airliner flight control systems?
Are the new systems of today built with the same CPUs and programming languages and development software as those of 20 or more years ago?
By new I mean that these systems are currently being designed for future airliners, or have seen service for the first time recently.
Any specific examples of new designs as used in a major latest-generation airliner (the A350 and 787 be the most obvious examples) would be better than general answers.
I'm interested in examples from any flight-essential systems (but not, for example, on-board entertainment).
As part of this question: does the industry tend to update its products through incremental updates to the microprocessors and programming languages it adopts, or does it tend to make once-in-a-generation shifts to new technologies? And, are there significant differences in the way airline manufacturers (as opposed to military/general aviation industries) approach this?

Note: I focused more on changes in aviation hardware and software than what's currently used since the question linked about programming languages is still current for "new" aircraft.  I do not wish to duplicate that question or its answers.  In my opinion C++, C#, and Ada will probably be the dominant programming languages for avionics for the next decade at least.
First, you've got to understand the life cycle of aircraft.  Many aircraft are in service for more than 30 years.  The avionics do get updates (whether adding new features, fixing bugs, or adding in compliance to meet mandates). However, the bulk of the work is done during initial development of the software and hardware.  The configuration is then mostly fixed until that generation of avionics is replaced by the manufacturer or retrofitted by another manufacturer.
So What's Changed in Practice?
If the avionics goes through a generational update (like CRT's to LCD screens), anything changed has to be worth the cost, so usually not much is changed.  Maybe the CPU, but definitely not the programming language. For example, the G1000 was out for 12 years before releasing another generation of hardware (although in the meantime they published numerous software updates for hardware compatibility and synthetic vision and such).
Similarly, Avidyne Entegra was out for five years and continuously adding major features like data link weather and LPV approach before it finally upgraded the hardware in release 9 in 2009.  Falcon jets like the Falcon 900 had a software and hardware update to their avionics in 2011, but that upgrade was based on Primus Epic family of hardware and software, whose first generation was already 9 years old.  I believe all the 900's were still running the old 1996 hardware before the 2011 upgrade.  On the other end of the spectrum from these slow upgrades, the military's JSF system is designed to be upgraded easily every few years (but they don't say just how often).
Why Not Make More Frequent Upgrades?
What drives value in avionics isn't usually exotic new features and definitely not computing performance.  Value is driven by reliability, compliance to mandates, and safety-compliance.  This requires features that are simple enough for the engineer and the pilot to understand and are robust enough to have hundreds of lives depend on it. So the new features being added generally require little extra performance, and there's little incentive for cutting-edge technology or the latest programming paradigms like cloud computing, machine learning, or object orientation.
An engineer at Rockwell Collins stated something that applies to all avionics "In the past, we struggled to fit everything we needed to do into the size of processor and speeds we had and how to get all those bits over the interfaces we had. With the processors we have now and fiber interfaces, that is no longer a concern... Now the problem is how to manage and design good, trouble-free software and test all the lines of code involved. So now that we have all the processing and bandwidth we need, we have to make sure we can use it and not design ourselves into a corner."
Verification is one of the biggest driving factors (and costs) in processor and programming language usage.  All hardware and software must have a safety level attached to it, with the most critical functions (like avionics for autoland) considered "Level A" meaning such a failure of the avionics could be catastrophic.  In order to achieve the stringent safety requirements for Level A software (which is often one such failure per 10^9 flight hours), the software and hardware need to be exhaustively tested to ensure nothing will ever go wrong.  That includes covering every condition on every line of code.  Most tools developed to work with your programming language and software architecture needs to be formally verified (usually called "qualified") as well. On top of that all, costly flight testing needs to be done to evaluate any changes.  This creates a lot of inertia and means a complete overhaul of an existing product or starting from scratch for a new product just to get a "faster system" is often not cost-effective.
What about support for new CPU features?
Virtualization (allowing different OS's to act like they're running by themselves but are actually running with a layer between themselves and the bare hardware) and multi-core processing is now supported by some real-time OS's for commercial off-the-shelf processors. These have to follow the standards in DO-332 and other materials.  According to my 2013 text, this is still in the investigatory phase and no avionics with these features have been certified.  The main issue is that multi-core processors don't just have more features, but they have more features that are not comprehensively documented or testable. For more information on issues with use of multi-core see the FAA's CAST 32 and this presentation.

"Virtualization (where different processes each act like they're running by themselves but are actually running on a virtual machine)"... hum, the definition I have for virtualization is: CPU, memory, storage, I/O, and network seem to be exclusively owned and used by an OS, while actually multiple OS instances run on the same resources that a virtualizer is sharing between them. The virtualization can be by hardware, or by software.

Thanks @CodyP for this detailed and informative reply to the question. There are many matters here that deserve closer scrutiny, but two that stand out: 1) multi-core processors [have] features that are not comprehensively documented or testable - in other words future generations of CPU may turn out to be essentially unsuitable for critical aerospace applications! 2) there may come a time when the microprocessing hardware that these very conservative systems are built around simply becomes unavailable - will that perhaps be a trigger for from-scratch software/hardware redevelopment?

@mins Thanks for the catch!

Comprehensively documented or testable means there are internal hidden variables, and features that aren't fully described.  It will probably eventually be worth the extra verification difficulty to use multi-core CPU's. Worst case scenario you can turn a core off. However don't forget that 1) We're talking about embedded processors, not desktop or mobile processors, so it's a different market and so you'll see different processors being used 2)Even the consumer electronics market alone is very diverse.  After all, Apple is still putting Apple dual-core processors in iPads.

For virtualization, a major concern is that the more things you run on one machine, the more you're giving yourself a "Single point of failure". When something breaks on an airplane, we like redundancy and system independence: the fewer things that break when something else breaks, the better!

@JonStory I'm not sure how much virtualization affects single point of failure analysis but I can guess that if implemented correctly it wouldn't be that different from current IMA's, where you might have maintenance and fly-by-wire running side by side on a single card. Single point of failure is mitigated by having several separate such computers. However, cpu virtualization wasn't designed with the same robust partitioning that we use in avionics software so partitioning would be a challenge.

Yeah it's definitely possible to do it - as with anything, we can just have two... it's just that you're piling more into one system: which is great for cost cutting, but not necessarily ideal for safety-critical reliability, where "Each system does one thing, all of one thing, and nothing but that thing" is often more useful. It can certainly be a managed risk, but it's a risk nonetheless

Downvoted because whilst it is an in-depth answer it doesn't really answer the original question about processors or programming languages.

Definitely not C#, I guess you mean just plain C. C# is garbage collected, something you'd definitely avoid on real-time systems.

Many factors go into selecting the programming language and the processor for each product, some of which are:

General purpose of the software system
Selected Design Assurance Level (A-E)
Hardware constraints of the product
Company experience with a language
Available development tools
Available verification tools

I believe the most common languages used in aviation safety critical systems are C and Ada, with C++ gaining more usage in the last 10 or 15 years.
Processors can range from simple 8 bit SO8 micros to PowerPC to multicore x86 or ARM System on Chips. Electronic Hardware such as PLDs and FPGAs are also becoming popular for certain work loads.

Welcome to Aviation.SE! Your answer could do with a bit more detail on what has changed to fully answer the question but is a good start. Many answers are edited and built up / improved over a period of time to add more detail.


text:
What, exactly, is a "co-pilot"?
When I speak of a co-worker, or a co-driver, I'm speaking of a mutual relationship and status (that's simply how the prefix co works in normal English) and I'm pretty sure it's what most people mean too.
When people speak about co-pilots on the other hand, it seems they might mean one of several things:

They are speaking of two pilots who happen to be working as part of the same crew, who are therefore co-pilots (which seems the most correct usage).
They mean a pilot who isn't the captain.
They mean the pilot monitoring rather than the pilot flying.
They think the aircraft has a pilot, and a kind of assistant pilot of lesser abilities known as a co-pilot.

(This last seems to be strangely prevalent, as if people imagine an airliner might be crewed by a fully-qualified professional and by some sort of assistant whose job is the aviation equivalent of holding the ladder, who looks forward to the day they'll be allowed to climb up it themselves.)
Weirdly, I have actually heard air crews use co-pilot in ambiguous ways, as though even they have given up trying to use the word with care; once I heard an announcement in one language that referred to the captain and the first officer, and then immediately afterwards in another to pilot and co-pilot.
Questions about co-pilot
It seems reasonable to say "my co-pilot" when speaking of a fellow crew member. However:

Does "the co-pilot" have any meaning (note the use of the definite article)?
Is co-pilot ever a rank?
Does the term appear in aviation regulations?
Is it used in crew management policies?
Is there indeed any standardised or formal use of it within the industry?

It probably depends on the country. In France Commandant/Copilot are used respectively for Captain/First Officer in the US. In my view this is clearer, as Commandant/Copilot are roles (pilot in command, and pilot), not rankings.

Hmm.. good question. I never thought of it that way.

I'm not sure that the FAA really recognizes a co-pilot, almost all regulations refer to the other crew member as the second-in-command, and even has a type rating as such. It mirrors the FAA's push to recognize the people in the cockpit as a team, not superior/subordinate.

This seems almost like an English Language stackexchange question.

........Jarvis?


text:
How, typically, do passengers and crew behave in a real-life airliner evacuation?
Two parts to this:

Do passengers tend to behave in ideal ways?
How do the cabin crew behave?

We know what's supposed to happen: the passengers are supposed to follow instructions, leave possessions behind not inflate their life-jackets inside the aircraft, and so on.
To what extent does this actually happen?
I know for example that passengers have inflated their life-jackets inside the aircraft (with tragic results, in the case of Ethiopian Airlines 961, where some passengers became trapped inside and drowned as a result). I can bet that some passengers will inevitably want to insist on gathering some tremendously important belongings.
I assume also for example that the management of the emergency exits isn't simply left in the hands of the passengers sitting next to them, but that the crew as far as possible take charge, and that generally they become ferociously assertive and intolerant of any nonsense from recalcitrant passengers.

You have answered your own question.  Passengers generally do not behave according to the ideal model and yes, crew become ferociously assertive.

Look for the life vests on this image of US Airways 1549 ditching in the Hudson. 33 passengers out of 150 got their life vest with them when leaving the cabin, and only 4 completed its donning.

I had a teacher in high school who said that she previously worked as a flight attendant.  She once told a story that she accidentally inflated a life vest during the safety announcements.

I suppose it highly depends on the cultural background of passengers. I would guess Japanese passengers will tend to follow the instruction in a calm behavior whereas occidental one would do so only if they understand why (passenger management from crew far more critical)

@ManuH The first statement is somewhat correct/okay, but the second statement contains stereotypes.

@Steve - stereotypes have basis in fact. They're usually exaggerated, and, of course, overly broad, but as generalizations of large groups are often reasonably accurate. Even if they point to an ugly truth. end off-topic ramble

I recall seeing a report once that claimed (with some experimental support IIRC) that a mad dash to the exits was a more efficient way to empty a plane than an orderly evacuation was. But I can't recall where I saw this, and don't recall the details or the quality of the source well enough to guess whether the conclusion was valid.

You are asking a typical outcome from a very highly untypical event... Quite hard to give a definitive answer

In real life what happens ranges from cool, collected action to panic. In an accident with many people there will a spectrum of behavior. In an accident things happen quickly and even with extensive training many people will become stressed or panic and react incorrectly. I was once with an instructor who had thousands of hours of flight experience who panicked on a training flight while I remained calm, even though I was only a 20-hour student at the time. You simply can't predict what any given person will do when a crisis occurs.
On Flight 1549, the ditching of an airliner into the Hudson River, the passengers and crew remained relatively calm, but still made many mistakes. For example, only 33 of the 150 passengers retrieved their life vest, and only a few of them put it on. Most of the 33 who had the jacket simply carried it in their hand. (It is impossible to put on a life jacket in the water, which is why it must be put on before exiting the plane, but only inflated after exiting a plane--quite a tricky requirement if you think about it.) The crew failed to secure the plane for ditching which caused it to take on more water than it should have.
Concerning the Ethiopian flight, I think the life-jacket-inside-plane thing is just concocted. That plane ground looped and broke apart on impact and was flooded with water. Who drowned and who did not had nothing to do with the little water wing things that pass as life jackets on a plane. I think officials just found a few dead people inside the plane with jackets on and made up that story. In all likelihood, the fact that they were wearing them had nothing to do with their death. Whenever an accident occurs, officials always look for excuses and blame and the favorite one is the victim wasn't (or was) wearing a helmet-seat belt-life jacket or whatever. It's just a political game.

In the emergency landing of Emirates Boeing 777, EK521, 300 souls including 282 passengers successfully evacuated an aircraft that landed with only the left side of the main undercarriage extended, and was already on fire before it had stopped moving.
The aircraft was severely tilted over to one side, which must have made movement inside very difficult. Within a few minutes an explosion threw large pieces high into the air (possibly a slide or wing part) and the fuselage was gutted by the fire.
So at least in one case where one might expect very frightened passengers packed into a burning airliner to panic dangerously, it appears that they did not, and evacuated safely (one crew member was apparently hospitalised).
It's only one case, not enough to describe what typically happens, but please add to this answer with further examples to make it so.

The Gimli landing recount by crews, which was the topic of a Mayday document, is full of details about the passengers mindings and actions, including the evacuation.


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Would there be any advantages to a wing with a concave upper surface?
A wing with a concave upper surface could have the same area as one with the normal convex shape of an aerofoil.
I can think of many potential disadvantages: additional complexity of design and construction, reduced volume for fuel tanks, having rain fill up rather than run off the the wing.
Could there be any advantages to such a design? Has it ever been tried, or studied?
For clarity, this is the kind of cross-section I have in mind. Yes, it's ugly, and I don't think that better draughtsmanship would improve it.

aerodynamics-wise you would have earlier flow separation (another disadvantage), if I understood you correctly. Otherwise, you you are speaking of "upside-down" airfoils, they produce less (or more negative) lift given the same AoA.

No, I don't mean upside-down aerofoils - I mean an aerofoil that has the same upper and lower area as a "normal" one, but that achieves that on the upper surface by curving back inwards, rather than outwards (yes, it would look ghastly).

then I repeat my first point: aerodynamically, I don't think it makes sense

I'm pretty sure this would create a lot more drag than lift, wings are curved outwards on the top for a reason, even in nature.

It's used when lift must be oriented down, like for a "car rear wing/airfoil"..

@mins I specifically don't mean an upside-down aerofoil; I mean one that will produce lift.

@mins -- or a horizontal stabilizer?

How a totally concave upper surface (i.e. negative camber)  can be oriented so that the air streams are accelerated downwards to produce positive lift? The AoA must be very large before reaching the point of positive lift, but drag would already be huge. This reasoning is not a demonstration indeed, however Ron's answer and use of the airfoil simulation bring elements sustaining it.

@UnrecognizedFallingObject: Ah yes, I wonder why this is not the case in general. I see often this at most a flat upper area, with the elevator creating the overall camber.

The idea behind this design seems to be that the principal cause of lift
of a wing is that the top has a larger area than the bottom, so if we
substitute a top surface with a different shape but the same area, we will
still get similar lift.
This is the idea behind the equal-transit-time theory of lift,
which is incorrect, disagreeing in several ways with
with actual observations of air flowing past airfoils and the
lift forces that result.
NASA has produced a basic but thorough refutation of this theory;
among the points they make are

The lift predicted by the "Equal Transit" theory is much less than the observed lift, because the velocity is too low. The actual velocity over the top of an airfoil is much faster than that predicted by the "Longer Path" theory and particles moving over the top arrive at the trailing edge before particles moving under the airfoil.

and

There are modern, low-drag airfoils which produce lift on which the bottom surface is actually longer than the top.

What you generally want in an airfoil is for it to establish streamlines
that carry the air at very high speed over the top and shoot it downward
past the trailing edge. The speed is not determined by the surface area
or length along the top surface; the speed is determined by other things,
and two air molecules that start near each other but go on different sides
of the wing (one on top, one on the bottom) get to the trailing edge when their respective speeds carry them there, generally not at the same time as each other.
Putting a big hollow space on top of the wing
where the air can pile up and then forcing it over a second hump to get
to the trailing edge seems counterproductive.
It might just lead to the wing stalling at relatively low angles of attack,
which would limit the amount of lift you can get from it.
But I am not an airfoil designer, and I don't know exactly what the result would be.

The equal transit theory isn't really itself part of the question - the main point is that instead of continuing to go up at a certain point on the wing, its curve would go down (so all other things remain equal, as much as possible). The latter part of your answer is the thing I am hoping for some enlightenment upon - what would the air do in that hollow? And would it have some dramatic effects around/above mach 1?

@DanieleProcida Why don't we just put the wheels on top of the car? It shouldn't matter since we have the same amount of wheels either way.

@immibis What is the point of that sort of sarcastic remark?

@DanieleProcida You are saying that a concave wing should work if it has the same surface area. I am saying that a top-wheeled car should work if it has the same number of wheels. In both cases, we have focused on something that is mostly irrelevant to the actual problem at hand. Just because a new wing or car design has the same surface area or number of wheels as one that already works doesn't mean the new one will also work,

@immibis No, I wasn't 'saying'. I was asking. It was a question, about something that seemed interesting to me. That is what StackExchange is for. You'll notice that although StackExchange has a points system, you don't get points by making sarcastic comments about other people's questions.

A wing with an inward (concave) surface on the top will generate negative lift for many positive angles of attack, and really not much lift at all. Curving the top surface is basically creating an upside down airfoil (because lift is negative).
Take a look at a 0° angle-of-attack on a wing with a -14.24% camber:

You can see we are generating a lot of negative lift (-3955 lbs) and a lot of drag, resulting in a large (negative) L/D ratio.
Lets increase the AoA until we get a slightly positive lift coefficient:

You can see that the AoA is extreme for a small amount of lift, barely overcoming drag. The AoA of 15.2° is required which brings the airfoil basically into stall because the flow is going to quickly separate from the wing.
Compare all this to a "normal" airfoil:

At a small 3.5° AoA, you are generating 1000+ lbs of lift and only 90lbs of drag, with a L/D ratio of 11+.
If you would like to play around with airfoils and see the results like I have above, you can download NASA's FoilSim Program

Thanks for this detailed answer, and the reference to the FoilSim program. (I've downloaded it and after much fighting with Java have it running.) It's interesting - but in fact, I don't think it's even possible to model the shape I'm describing in the question.

@DanieleProcida How did you get FoilSim working?? I've had the program files sitting there for months now after giving up on getting them working even after changing Java settings

@Xylius I downloaded it, opened the OS X Java system preferences, added Foil.html to the list of specially-allowed applications, and opened that in Firefox (it didn't work in Safari).

@DanieleProcida Note taken, thanks!

Well, wing produces lift by accelerating the air downward. That's a result of third law of motion (principle of action and reaction). And it applies at each point along the wing—the lower the pressure, the higher the lift, but also the downward acceleration of the air flowing over the wing.
Now that only works to a certain point. If the surface curves too fast, the air won't be able to follow it any more due to inertia, will detach and the pocket underneath will fill with stagnant air at ambient pressure, eliminating the suction and the lift with it. That is stall.
Normal wing distributes the acceleration of the air along the chord. However, as the air follows your shape, it would accelerate downward a lot in the first part, then return up somewhat before the second hump and accelerate downward a lot again over the second hump.
Your wing needs higher curvature at the two humps to compensate for the concave part generating negative lift. Mainly the first hump is critical, because increasing angle of attack only increases the curvature near the leading edge (while flaps increase it further aft). So I would expect your wing to stall earlier.
I would also expect the wing to have higher form drag, because there would be more changes to the flow conditions and each such change means losing some energy to viscosity.
Also above compares wings with the same coefficient of lift. To achieve it, your wing would probably have to be thicker as it needs to compensate for the negative lift in the middle part. Which is another reason for having higher form drag, too.
No advantage in sight anywhere.

Makes me wonder why no answer mentions that there is no space for a decent wing spar. The poor aerodynamics can be overcome; the low stiffness and much higher structural mass are the killer.

@PeterKämpf, I suppose because the aerodynamic problems are relatively easy to see with some grasp of physics, but it takes some experience to get idea where structural problems are to be expected—and you are one of very few here with such experience.

@PeterKämpf, also, perhaps the wing would have two spars in the two humps. The humps won't be thinner than normal wing.

If you assume the same aerodynamic qualities, the spar could be much stronger ;-). And the depressed center also reduces torsional stiffness, with no benefit whatsoever.


text:
Which aircraft have made notable use of lateral asymmetry?
I'm asking about functional asymmetry - doors on one side but not the other wouldn't count.
Examples
I can think of three examples:

experiments with oblique wing designs, such as NASA's utterly hideous AD-1, designed apparently by Burt Rutan
displaced fuselage designs, such as the Blohm & Voss BV 141 or (another Burt Rutan aircraft), the Boomerang
all single-propeller aircraft, in which the torque of the engine exerts asymmetrical forces on the aircraft

Symmetrical asymmetry doesn't count
(Then there are some that I don't think really count - for example, the Wright brothers' Flyer 1 placed the engine and the pilot side-by-side, but since they were intended to balance each other out and the twin propellors were symmetrically placed, that counts as an attempt at symmetry as far as I am concerned!)
Other examples, and the reason for their asymmetrical design
Are there any other good examples? The more ugly and wrong-looking, the better.
I'm interested in the problems that the asymmetry aimed to solve - for example, oblique wing designs aimed to procure aerodynamic advantages (which turned out to be at the expense of handling issues), or Rutan's Boomerang which "was intended to be a multi-engine aircraft that in the event of failure of a single engine would not become dangerously difficult to control due to asymmetric thrust" (Wikipedia)
Visual reference
Just for reference, here's the AD-1 (NASA, via Wikipedia):

... and the BV 141 (Deutsche Bundesarchiv, via Wikipedia):

Burt Rutan's Boomerang is asymmetrical, but I wouldn't call it ugly.

747 with a spare engine mounted...

The Wright Flyer's wing was 4 inches wider on the side of the engine, because the Wrights wanted to compensate for the heavy engine. Wouldn't that count as a functional asymmetry?

Don't be silly, why would anyone make an assym... oooh... I learned a thing today!

@PeterKämpf I didn't know about the wing length, I guess that probably counts!

Don't know if you found it, but there's actually a short Wikipedia page on asymmetrical aircraft.  It also talks briefly about the design considerations involved.

there are many GA aircraft that have an asymmetrical engine mount and/or an asymmetrical empannage to counter P-factor.

@rbp: Many propeller-powered fighter aircraft had cambered vertical tails to help counter torque effects. I guess that is also a functional asymmetry, but not ugly or wrong-looking enough to count here.

Some single-engine fighters of the WWII era had one wing extended to help counter engine torque.

There are quite a few asymmetric aircraft, most of which are,

experimental
engine test beds

A good example of experimental aircraft is the NASA F-16XL

F-16XL with supersonic laminar flow control experiment (black area on left wing, front) or "glove." Image from nasa.gov
Aircraft used as engine test beds are usually asymmetric. The following image shows a B-47 Stratojet used as engine test bed for the the Orenda engine earmarked for Avro Arrow program.

Image from silverhawkauthor.com
A closeup of the rear:

Image from google
English Electric Canberra PR9s had offset canopies.

By MilborneOne - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=13266605
So did the de Havilland Sea Vixens.

By Yeovilton_Vixen_2009-001.tif: Nigel Ishderivative work: Cobatfor - This file was derived from  Yeovilton Vixen 2009-001.tif: , CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19477903
Of course, all 'conventional' helicopters (with tail rotors on one side) are asymmetric, but I don't think that's what you're after here.
Also, see this page and the Wikipedia page on asymmetric aircraft. As a disclaimer, I wouldn't call any of these aircraft 'ugly'.

I have never seen or heard of most of these aircraft! This is fascinating. +1 for the great question and +1 for this great answer.

The Orenda ingests the boundary layer of the wing in the configuration used on the B-47! What were they thinking? This is no way to conduct proper testing.

If we count aircraft with offset parts then there are probably more aircraft than one might expect. Even the A-10 has an offset nose landing gear in order to accommodate the gun.https://c1.staticflickr.com/9/8722/16696627519_9142f36d14_b.jpg

The observer in the Sea Vixen was positioned under the hatch to the right of the offset cockpit canopy; this was a frangible hatch where the ejection seat would shatter the hatch in the event of an ejection. Unfortunately, it was not always as frangible as it should have been.

All aircraft with external storage that dump only one become instantly asymmetrical. A particularly extreme example might be the Heinkel He-111 H22, which was designed to carry a V1 to a launching point in order to attack targets beyond the reach of the fixed launch catapults, or the B-52 used to carry the X-15 aloft.

Heinkel He-111 H22 with FZG-76 (picture source)
Even after dropping the cruise missile, the He-111 H remained an asymmetrical configuration, because the tip of its glazed nose was offset to one side, so the front gunner would obstruct the pilot's view less.

Inside view of the He-111 cockpit (picture source).

B-52 just after launch of the X-15 (picture source)
Also here the aircraft remained asymmetrical after having launched the X-15 due to the large pylon used for carrying the X-15.

The Rutan Voyager (World Flight, 1986) two wings are not at the same position along the length of the aircraft. To save weight, their non-tapered spars are bolted together in the fuselage, so one wing is one spar thickness ahead of the other. With a wingspan of over 100 feet, it isn't very noticeable.
It also has two vertical stabilizers but only the starboard one has a movable rudder. To cut down on questions about that, they put a line on the port one that looks like a rudder gap using an ink marker (lighter than paint!). Lower cruise drag and weight at the cost of terrible rudder performance asymmetry (right rudder response was fine; left rudder response almost nonexistent).
This learned from conversations with Dick Rutan, the Voyager's pilot, in 1985/1986.

Another Rutan design (I think his earliest asymmetric) was the Ares "mudfighter" with a 25mm cannon on one side of the cockpit, and the turbojet air intake on the other. The design was intended to keep the pressure waves and nasty combustion gasses from the cannon from being ingested by the engine.
The NASA X-15 Active wasn't asymmetric by design, but was designed to induce asymmetries (to simulate failures, or damage, up to and including loss of an entire wing).

The M.C.202 actually had wings of different sizes to compensate the engine/propeller rotation:

As rightfully requested, here are some pictures from the video:

Many fighter aircraft of that period had cambered vertical tails to help to counter torque effects. This is also a functional asymmetry.


text:
How many serious airline accidents have been caused by design faults alone?
That is, in the chain of events that led to death or injuries in an airline accident, how often has a design fault been solely responsible?
By a design fault I mean a problem such that even if the equipment:

were maintained and operated to the highest possible standards
flown in ideal conditions
by pilots who committed no errors
unaffected by manufacturing defects
endured no bad luck

eventually it would still inevitably eventually kill or injure its passengers.
I can think of only two examples: the early Comet's square windows, and the Boeing 737 rudder power control problem.
All the others I can think of include errors of piloting, manufacture, maintenance or just plain bad luck in the chain of causes.
Are there others?

I don't know if the dH Comet's windows meets your "flown in ideal conditions" criteria. It's just that "ideal conditions" in that case weren't the same thing as the actual operating conditions, even if the aircraft was operated within its intended operating envelope. You might want to reconsider that criteria.

I'd agree the Comet is a good example. Most others would have been early aircraft that were built and crashed on their very first attempt to get airborne, at times when aerodynamics and other relevant sciences were so poorly understood that people designed aircraft through trial and error basically.

The Comet was flown as intended, in the conditions expected, that it should have been able to deal with by design. Even if the Comet had only flown in perfect conditions, eventually it would have succumbed unexpectedly.

I think it is difficult to trace one single cause. Comet's windows: it was know the fatigue problem on windows. Just the procedures were to check after X hours, and not after Y cycles (that aircraft did a lot more short flights then expected). So more testing/procedural problem. OTOH "design" is very open. A optimal designed aircraft should reduce/remove most of other problems.

The problem wasn't that the Comet's windows were square(ish). They had rounded corners, just not as rounded as modern windows.  The root issue was the use of insufficient material and rivets to achieve the strength and fatigue resistance with that particular shape.   They thought it was sufficient, but there were errors in calculations.  If they'd made the corners beefier in the first place it never would've been a problem.  Making them round later on was just a lighter solution than a beefier square.

@JohnK: There are both ways to look at this issue, and both are equally correct. Of course it was a combination of shape and strength, but the better (= lighter, more efficient) design is to use round windows. Therefore, blaming the shape is not wrong at all.

@PeterKämpf well I'm not sure I'd go quite that far, but it's fair to say they got themselves into trouble by cutting corners hahahahahahhahaha....

The Douglas DC-10 - The door latching mechanism was not robust and the design of the safety indication was flawed. In the Paris incident Douglas tried to blame the handler who closed the bulk compartment door for using excessive force when latching the door but ultimately the design was at fault.

Nitpicking, but that incident was caused by a combination of a design flaw and incorrect aircraft handling, not solely the design flaw. Had the door been closed properly it's unlikely a crash would have resulted.

I don't think the DC-10 fits. There were design flaws that were later remedied, but I think that in each case the design flaw was a contributor, not a sole cause.

The fact that the design was modified as a result of the crash shows that the initial design was flawed. Modifications to the system as required by a service bulletin were not carried out properly.

Another issues was the insufficiency vents between the lower and .main decks. In the WIndsor Locks incident the collapse of the aft cabin floor took out the control cables to the tail due to differential pressure between the lower and main deck. Additional vents were required so that pressure could be equalised without compromising the cabin floor.

Yes, the design had a flaw. But the design flaw was not solely responsible; you even mention incorrectly-performed modifications.

I'd say British Airways flight 38 qualifies. Flawed design of the fuel/oil heat exchanger allowed ice to block fuel flow. The aircraft was operated within intended limits and the crew did everything correctly. It was not a maintenance issue nor a manufacturing error.

This was the first serious incident with Boeing's 777.
For further reference:
Wikipedia: https://en.wikipedia.org/wiki/British_Airways_Flight_38
AAIB report: http://www.airsafe.com/events/reports/british-airways-b777-flight-38.pdf

The Douglas DC-6 apparently had a design flaw in the cabin heater that caused one fatal accident and another emergency landing in 1947 before the design was corrected:

https://www.pprune.org/archive/index.php/t-355634.html
https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_the_Douglas_DC-6

The Lockheed 188 Electra had a design flaw with regards to the engine mounting that caused catastrophic resonance and broke off the wings of two aircraft before it was corrected:
https://en.wikipedia.org/wiki/Lockheed_L-188_Electra

One of the early ones is the crash of a BFW M.20 on the Berlin-Goerlitz route on April 14, 1931. In a gust the rear fuselage was twisted by 60°, the tail surfaces almost broke off and the aircraft crashed. The crash investigation concluded that the design was good enough to satisfy the certification requirements, but that flight loads exceeded those. As a consequence, the certification loads were doubled.
Also, the rudder hard-over with the early Boeing 737s comes to mind. Those accidents caught the poor pilots in a trap. And maybe the first deep stall with the One-Eleven in 1963. Later accidents with the Hansa Jet and the Trident could had been avoided had the engineers and test pilots studied the One-Eleven accident better. Tupolev did and increased the tail size of their Tu-124A (which became the Tu-134) by 30% as a reaction.
The 1991 Lauda Air Boeing 767 uncommanded thrust reverser deployment might also fit. It happened before, in 1990, on the C-5A when the thrust reverser of the No. 1 engine deployed right after takeoff. Similar to Hawker-Siddeley before them, Boeing refused to learn that lesson and tried to cover up this design flaw.
Borderline case: The Kegworth air disaster, when a fan blade on the uprated CFM56 engine of a Boeing 737-400 broke and the different sourcing of flight deck air caused the pilots to shut down the good engine. It turned out that the engines had not been sufficiently tested and the pilots had insufficient familiarity with the engine instruments, so they came to their wrong conclusions (which would had been correct on the earlier 737s).

De Havilland Comet (structural problems, BOAC Flight 783 and 781 crashes in 1954 resulted grounding the entire fleet).

The question is about airliners, not experimental aircraft. The only airliner in this answer is already mentioned in the question.

The question has been edited.

The infamous Boeing 787 battery problem caused at least one emergency landing and evacuation, with a small number of passenger injuries:

"There was a battery alert in the cockpit and there was an odd smell detected in the cockpit and cabin, and [the pilot] decided to make an emergency landing," said Osamu Shinobe, an ANA vice president, at a news conference.
ANA said that the 129 passengers and eight crew were evacuated, with a number of people sustaining minor injuries.
The Reuters news agency reported that five people were injured, while Bloomberg said that one person was sent to hospital. ANA officials were not immediately available to confirm the figures.

Embraer Bandeirante
Pitch trim switch causes trim runaway. Crew puts excess stress on control system. Tail breaks off.
NTSB report

I replaced your link with the original PDF on the NTSB website, which hasn't been mangled by OCR (random fonts like a cut-out ransom note and, e.g., "Provincetown-Boston Airlines" becoming "Provincetown-Won Airlines", reference to "visual fight conditions", "Plight 1039", etc. just in the abstract).

Thanks, should have looked at it closer.

D-LZ129 Hindenburg, operated by the German Zeppelin Airline Company (Deutsche Zeppelin-Reederei).

The cause of the accident has never been determined conclusively.

Also, if design was the sole cause, why would the airship have flown successfully previously? Design might possibly have played a role in the Hindenburg disaster, but that doesn't mean the cause was a design fault alone.

Also while the cause has never been determined conclusively, it is mentioned that it was not maintained to highest standards and accumulated damage from previous flights is cited as possible contributing factor. So it does not qualify for that reason.


text:
How do messages get from the destination airport to a pilot?
A captain waiting in her airliner for take-off at an airport might inform her passengers:

We'll be waiting another ten minutes before we're able to take off, as traffic is very busy at [destination], and we have to arrive in accordance with the landing slot we've been given.

How did that information reach the pilot, and what route did it take?
The answer I am looking for might be something like: the slot controller allocates the slot in the local slot control system database. This is communicated via a dedicated digital radio satellite system to ATC at the departure airport. ATC informs the local despatch controller by telephone or short-range radio. Finally, a runner is handed a slip of paper with the details and personally puts it into the pilot's hands.

Related: What are the differences between “ground stop”, “ground delay”, and “gate hold”? and Is ATC connected to the Internet & why?

Related: https://aviation.stackexchange.com/questions/35315/how-much-does-it-cost-the-airline-if-an-aircraft-misses-its-take-off-slot

When the crew got their clearance for the trip from Clearance Delivery over the radio in the flight deck, it would've included a departure time window with the delay, and they may have been told by the CD controller why, or may have figured it out for themselves because it's a routine occurrence for the airport they were headed to (like Chicago).
Or, they were told prior to that during the planning brief with Operations. All the planning and filing is done by specialists in the airline's Operations department. The crew just shows up at Operations and picks up a package with everything prepared; the route, weather, provisional loading, fuel, etc. Going to an airport with a reservation protocol in place, they would have been briefed on that by Operations. That is all provisional however, the final routing, loading, fuel etc is determined when getting ready at the gate, and also when they get their ATC clearance by calling Clearance Delivery over the VHF radio before programming the Flight Management Computer.

What is the route the information takes, from the point at which someone or some system allocates a slot for landing, and that information is finally conveyed to the crew?

All the planning and filing is done by specialists in the airline's Operations department.  The crew just shows up at Operations and picks up a package with everything prepared; the route, weather, provisional loading, fuel, etc.  Going to an airport with a reservation protocol in place, they would have been briefed on that by Operations.  That is all provisional however, the final routing, loading, fuel etc is determined when getting ready at the gate, and also when they get their ATC clearance by calling Clearance Delivery over the VHF radio before programming the Flight Management Computer.

Thanks for adding that information @John-K - can you add that to the answer?

Of note, clearance delivery over CPDLC data link is live at all major US airports.

First, there are two different methods of regulating traffic. First, there is the CTOT or "Calculated takeoff time". This is time when flight should be airborne, and is derived from all the airspaces the flight will go through to ensure that any those airspace will not get too congested. So, it is well possible that a flight from say London to Rome is kept on ground because certain ATC sector in northern France has a lot of flights planned to fly over it at the same time. Not all the flights are given a CTOT time. By changing the route or the planned altitude a little the flight may get rid of the CTOT. Flight dispatchers are responsible of this.
Secondly, at many busy airports, there is TSAT or "Target start-up time". As the name implies, this is the time that the flight should leave the gate. The purpose of TSAT is to shorten the queues at the runway holding point. It is better to wait at the gate than wait with engines running.
If flight also has a CTOT, TSAT time is adjusted accordingly so that if flight leaves the gate in time it should be ready at the end of the runway at CTOT time. TSAT time is set only by the departure airport so usually when it is in force, all flights are given a TSAT time. If they miss it, they will wait at the gate until they get a new TSAT. Usually it is soon, but sometimes there can be significant delay if there is lots of outbound traffic. This might be also true if flight has also missed its CTOT due to not being ready at the required time.
The methods of communicating these times to cockpit vary a lot. ATC gives the times when the crew asks for enroute clearance at the gate. Also, in my company we get an ACARS message every time our CTOT time, if any, changes. Then, on the cockpit laptop we have a application that shows all the TSAT times in our home base. More than that, if there is a quick improvement and the flight has to leave pronto, the operations center will call the the plane on the company VHF frequency to inform about the immediate change. And on many airports, the TSAT time is displayed on Visual Docking Guidance System (VDGS) screen. And finally there is the gate agent who manages the turnaround, who should be aware of the current TSAT.